1. Technical Field
This invention relates to a grain drying system and, more particularly, to a combustible grain drying system for producing energy byproduct.
2. Prior Art
It is known to dry grain to enhance its storage characteristics. In a typical grain drying apparatus, oil or coal is burned to provide hot gases which are circulated throughout the grain to dry it. Such a process is expensive because of the high prices for coal or oil. Typically, such a grain dehydrator has an oil or gas furnace that produces hot gases for drying the grain. A cyclone-type separator separates the dried grain from gaseous odors, which are then re-burned for supplementing the hot gases from the furnace.
The burning of agricultural waste products to produce heat is also known. In this case an apparatus directs combustible material, such as the hulls of rice, to a furnace to produce a swirling flow of combustible products. A fluidized bed is also known for combustion processes wherein such fluidized bed reactors burn material. In each of these devices, the desired output heat is obtained by a heat exchanger in contact with the fluidized bed.
The cost of energy (dollars per million BTU's) from the burning of corn and wheat is comparable to that from oil, gasoline and liquified gas, but much higher (two to three times) than that from coal. While grain dust (emissions) represents about 0.4 percent of the total U.S. grain production, the available grain dust emissions are a viable fuel source for the approximately 8,000 country, inland terminal and port terminal grain facilities located throughout the United States. They provide a safe, nonpolluting way to eliminate a very dangerous pollution source. At an essentially zero resource cost, they provide a substantial reduction in grain-elevator heating and/or power costs.
Accordingly, a need remains for a combustible grain drying system for producing energy byproduct in order to overcome the above-noted shortcomings. The present invention satisfies such a need by providing a grain drying system that is efficient, cost-effective and adaptable to use on most typical grain dryers. Such a grain drying system advantageously provides steam for the production of electricity or general plant use. The system conveniently uses grain dust as an essentially free source of energy while advantageously resulting in very low amounts of pollution produced and emitted.